This disclosure relates to sofa beds, and more particularly to a convertible sofa bed configured to be either manually operated or electrically actuated to move the sofa bed between its sofa position and its bed position.
Couch/bed combinations frequently referred to as convertible sofa beds, generally include moveable seat and back portions which can be folded to a seating configuration and unfolded to a horizontal, generally planar reclined configuration for use as a bed. Suitable linkage is provided for pivotally coupling the seat and back portions. In some sofa beds, the seat portion of the sofa unfolds outward from the back portion which remains fixed in position, with the distal end of the thus unfolded seat portion supported by unfolding legs. In others, the back portion of the sofa reclines to provide, with the seat portion, a pair of generally flat, aligned support surfaces. Other approaches make use of extendable/retractable frame extensions at either the head or foot portion of the unfolded configuration to provide additional support surface area.
To date, manually operated convertible sofa beds have suffered from various shortcomings. For example, the absence of means for locking the unfolded assembly in the bed configuration allows the flat support surface to be easily rendered non-planar when weight is concentrated on a relatively small surface area, particularly along a median axis of the bed such as between the unfolded seat and back portions thereof. In addition, convertible sofa beds which require unfolding of the seat portion by pulling up on an aft, inner portion of the seat require considerable strength for unfolding. This precludes use of this type of folding sofa bed by the handicapped, feeble or those of advancing age. Further, some available pivoting linkage for convertible sofa beds is generally complicated and makes use of a large number of components which increases its cost and reduces its reliability and limits its usable lifetime.
Similarly, electrically actuated convertible sofa beds, requiring the use of a motorized device, have suffered from various shortcomings. Besides some of the shortcomings described above, poor placement of the motorized device in some prior art electrically actuated convertible sofa beds can make repair and replacement of the motorized device difficult. For example, U.S. Pat. No. 4,321,716 to Shrock et al. discloses an electrically actuated convertible sofa bed for use in a vehicle where a drive motor is located between the seat frame and the inner wall of the vehicle in order to maximize storage space under the sofa bed. Unfortunately, such a disposition makes repair and replacement of the drive motor difficult.